"Counter Stop" (正体不明(カウンターストップ),Shōtai Fumei(Kauntā Sutoppu)?, lit. "Unknown Entity") is the twenty-first episode of the Toaru Majutsu no Index anime series, and the first episode of the Kazakiri Hyouka Arc. It was first broadcast on February 26, 2009, and was directed Yanagi Shinsuke, storyboarded by Yanagisawa Tetsuya, and the script written by Nishizono Satoru.

Touma's long summer vacation that began with his encounter with Index is ended and the semester begins. In Touma's class, Himegami Aisa who was freeloading in Komoe's house appears as a transfer student. Meanwhile, entrusted to stay at home, Index discovers that lunch wasn't provided for her and reaches Touma's classrom and is immediately kicked out by Komoe. She wanders towards the cafeteria and comes upon a vending machine. Predictably, she does not know how to make a purchase until she is aided by Kazakiri Hyouka, who appears casually before her. Their relationship deepens and Index becomes friends with Hyouka. In the peaceful Academy City, a magician is confirmed to have infiltrated the city.

Contents

It is morning, and nothing queer has apparently happened to Touma's room. It is the start of the second school semester, and Index and Touma are enjoying their breakfast together. Index questions if Touma has to go to school, to which he realizes that Index would be alone for the entire. Index lashes out, stating that she did not say that she will be lonely, or like being alone. Touma ponders for a moment, and apologizes to Index, saying that she needs to stay inside for the entire day. Index's eyes glisten with her tears, as she asks Touma to come home as soon as he can. Touma casually finishes his breakfast, before replying Index with a vague answer. As he stands up, Touma suggests that after he gets back that they should go out somewhere. Index's face lights up, and agrees with Touma's suggestion. Touma begins to set out for school, and Index bids farewell, waving as she does so. Suddenly, after Touma goes out, Index grabs the sleeping Sphynx unexpectedly, and asks what they should do today. She rolls around the floor with the hapless kitten in her clutches, humming something queerly familiar. However, she stops, and with a face of abject horror, realizes that she has no lunch.

In the outside, pass trains and cars, Touma comfortably runs towards his destination. However, little did he know, that a certain person was fast running behind him. The person passes Touma by, and with a little gust of wind, Touma realizes who this person is, Biribiri. Touma calls out to her, and she stops. With a mean face, Mikoto asks if why he is so relaxed. He tells her that it's because so many things has happened and he is tired. Mikoto blushes and demands to know if the dating game they played yesterday was that tiring to him, to which Touma offhandedly says that was not the only reason. Hearing this, Mikoto demands to know if he has been doing "that" kind of things for other girls, too. Touma is surprised by this, and tells her that she is the only one who could calmly ask him such embarassing things, and runs off. Mikoto shouts out to him that it wasn't even for her as well, and slowly becomes red as she explains her point, though Touma no longer wants to debate her regarding this and just agrees with whatever she says, much to her chagrin.

He arrives at the parking grounds of his school, and the voice over of Touma mentions on how he is nervous because he lost his memories during summer vacation, feeling like he is a transfer student on their first day. A carhorn then blows off, and Touma sees that a small car passes him by, being driven by Tsukuyomi Komoe. Touma jests on how she shouldn't be able to reach the brakes with her feet, much to her chagrin, saying that she cans still drive even if her feet can't reach the brakes. Komoe berates Touma as they go to the school building together. Touma then notices the papers that Komoe is holding in her petite arms, assuming it is a pop quiz. Komoe says it isn't as she doesn't like pop quizzes herself, and tells that it is actually data that a friend requested her to gather. It is a paper regarding AIM dispersion fields, there Komoe lectures Touma on An Involuntary Movement, the weak unconscious field of power that is emitted by espers unconsciously. They finish their conversation as Komoe stops by the faculty room, noting that there are people dedicated in researching it.

Meanwhile, in the omynous eyrie of Academy City's General Superintendent, Tsuchimikado Motoharu appears with a red-headed teleporter wearing a Kirigaoka jacket. She looks tired, but smiles weakly as Motoharu thanks her for teleporting him there everytime, before teleporting away. Motoharu becomes serious as he brazenly demands the person inside a glass tube with the queer red fluid in it, on how he allowed a magician to break into the city so easily. The person says on how it does not matter, because as they are speaking, he is tracing the location of the intruder. Motoharu then sticks a photo on the glass tube with a woman in the focus, and tells the person in the water that the intruder is Sherry Cromwell, a magician of the Church of England. Motoharu reminds the man in the tube, as he knows, that if Sherry is taken down without care, it could lead to a breakdown of relations between the Church of England and Academy City. The person in the tube mocks the relationship, being "loving" neighbors who are each other's throats. Motoharu asks that he take out Sherry himself, being of the same church as hers, there would be little repurcussions as they are both magicians. As Motoharu turns away, the man speaks that he need not do anything, and Motoharu immediately means what he is trying to imply—he will be using Kamijou Touma again. The man says that it would shorten the time between two parts of his plans, to which Motoharu asks if its about controlling the Imaginary Number District. The man does not answer, and says that "it" is a restive horse that could rip apart the entire world, if the reins are not firmly held.

Back in a certain high school, everything seems to be normal, with Touma sitting on second row from the back next to window. Touma wonders where Motoharu is, and Aogami Pierce replies that he hasn't him as well. Touma jests that maybe, Motoharu didn't finish his homework, to which Aogami cuts off that he purposely held off in doing his homework as so Komoe can scold him, much to Touma's disturbance. The door slides, and in comes Komoe. She says that before starting the opening ceremony, they have a new transfer student, and tries to introduce her to them. However, Index, with Sphynx upon her bosom, instead appears in the classroom, somehow being able to find Touma's school. Komoe is surprised as well as Touma, who looks away from her. Komoe pushes her out, while someone is waiting outside in the classroom. Komoe gives Index and tells her to go home and not talk to strangers, as Komoe pushes Index away, the person waiting at the door goes in, and spiritlessly says that she is the transfer student—Himegami Aisa.

As Index hungrily roams the empty hallways of Touma's school, she comes upon the cafeteria, and one of those food coupon dispensing machines. She recalls on how Touma makes fun of her for not knowing any of the new-fangled gizmos, and inserts the money into the machine and presses an empty pad, much to her horror as the money has apparently been eaten by the machine to her. As she cries, there is a sudden tap upon her shoulder. A girl with brown hair tied with long sidetail, round glasses, and large endowments, she wears white blouse, red tie, and long skirt. Apparently coming out of nowhere, she tells Index that she needs to push the button, and shows her how to do it. The money comes out of the machine, much to Index's amazement. Index thanks the girl, and asks her name, which she says is Kazakiri Hyouka. Index later relates to Hyouka on how Touma was being mean to her, and on how he avert his eyes when he saw her. Hyouka tells Index that the school is not a place for outsider's to come, to which Index states she is an outsider. Hyouka replies that it's because she's a transfer student. Excited, Index says that she'll become a transfer student as well, and tells Hyouka on how she needs to know what to do about lunch. Hyouka says that her attire is too distinctive, to which Hyouka says that she has an idea.

Erstwhile, Touma wanders alone in the empty halls of his school looking for Index, knowing that she is the type to get in trouble. From his side, he hears voices, one of which is Index's, marveling at the current fabric technology. Angry, Touma rushes in and opens door, finishing one classic comedic setup. They were red all over, Index and Hyouka, as they are seen by Touma half-naked. Naturally, the conclusion appears next, and the scene pans into the blue sky of summer.

With bites all over his body, Touma sits with Index and Hyouka. Touma sighs, saying that he'd be home soon since there would only be an opening ceremony today. Index says that she'd have no way of knowing that, though Touma says that it's common sense. Angry, Index asks Touma the common things that "magicians" know, such as the direction and standing position of the caster in the formula used during the idol theory ritual of injecting telesma into crucifixes made in England, as well as the golden ratio needed for it to work, much to Touma's chagrin, as Index says this with a face full of sardonic confidence. Annoyed by this, Touma quickly changes the subject and asks Index who the person next to her is. Index says that she isn't sure, but confirms to Touma that she is her friend. Hyouka introduces herself to Touma, and he in turn exchanges greetings. Touma asks if she is a transfer student, to which she gives a nervous reply. Index however, suddenly jumps in, and yells at Touma for scaring her. Index then says to Hyouka, that despite his propensity to jump into problems for girls, Touma is a good person, and then gives Sphynx to her, to relieve her nervousness. She picks the cat up, and hugs, unaware that she is burying it in her large twin mountains. Touma notices, and promptly turns away before he is called out on this. Luckily, Sphynx escapes for another day.

Suddenly, a childish voice is heard, and they turn to see Komoe being angry. She states that she didn't see Touma at the assembly hall, so she went look for him. She turns to look at the people gathered with Touma, and asks why girls always trickle down to him whenever he is, and presumes that if he has an AIM field that does just that. Annoyed, Touma asks Hyouka to speak up, but they later realized that she has somehow disappeared.

As Index waits for Touma to return from their opening ceremony, Hyouka returns, apologizing for disappearing all of a sudden. Index states that Komoe isn't mad, and she need not worry about it too much. However, Hyouka points out that Index seemed sad, to which Index states that Touma was mad at her. She says that he didn't hear anything she said, and he didn't smile at all, and asks herself if Touma has started to dislike her. Hyouka says that since they fight with each other, only means that they are really close. Index asks why, to which Hyouka says that the fact they can fight means they can forgive each other properly afterwards, and states that you can trust that person to not cut the relationship even after a fight, and tells Index that Touma is the kind of person who would get angry over something for her sake. Although, Hyouka remembers that Touma is also a person who would come talk to you calmly even after seeing one naked. Speak of the devil, the ceremony is over, and Touma comes waving by into view. He tells Index that they should go eat, and it would be more convenient since they'd be going out after eating anyway. Touma also asks Hyouka to join them, and after Index's insistence, accepts Touma's invitation.

Meanwhile, a certain transfer student notices them from a short distance away.

As Touma tries to withdraw money for their little get-together, he is accosted by a tug of his sleeves by that person—Himegami Aisa. She asks why he is giving her a cold reaction even after transferring to his school, though Touma only grunts, Aisa immediately knows her position—a girl who goes unnoticed. Trying to save the situation, Touma asks Aisa if she'd like to hang out with them. Aisa is obviously inticed, but a look of disappointment is wrought upon her face as she curses the person who has put a yoke upon her that prevents her from going out with Touma. Aisa says that she cannot go because she was tasked to run an errand. That aside, Aisa asks who that person with Index is, to which Touma answers. Aisa tries to confirm if that person really is Kazakiri Hyouka, to which Touma says she is. Aisa says with an ominous air, that back in Kirigaoka Girls' School where she attended, she says that she saw Hyouka's name there as well. Touma asks if Hyouka is an esper with a rare power like hers as well, to which Aisa says she does not know. Aisa however, states that Hyouka's name always appeared in the top ranking test results, though no one has ever seen her in person, no one even knows which class Hyouka is in. Aisa says that she got a little curious and investigated something, and discovered that she is called Counter Stop, though most importantly, she is called as the key to the Imaginary Number District - Five Elements Institution. Touma is shocked by this, realizing that the mysterious Five Elements Insitution might actually exist. Aisa says that it is the institution that controls the administration of Academy City from the shadows. Aisa continues that a special facility was established just for reseaching her ability, which is dedicated to discovering the truth, not about Counter Stop, but of the Imaginary Number District. Aisa asks what a queer person such as Hyouka is doing here, and Touma says that she is a transfer student, though Aisa does not believe this as she is the only transfer student. Finally, after pondering for a moment, Aisa says to be careful, and leaves.

Index is excited as she, Hyouka, and Touma go down towards the Underground Shopping Center. After a small fit of excitement, Touma asks her if she wants something to eat, though expensive places, and long lines are out of the question, and like a child, Index states the opposite of what Touma said—somewhere cheap, abundant in amount, delicious in quality, and not too popular. Touma asks Hyouka as well, though she suddenly squirms into Index's back. Touma asks if he has done anything wrong, though Hyouka says he did not, only murmuring that he has already seen her body, though Touma did not catch this, and she just stays silent.

Back in a certain higschool, a woman wearing a green track suit, laughs on Komoe's predicament with Touma, and wishes that her class could be as lively as well. Komoe does not take this lightly, and states that Anti-Skill like her, seems to have a problem with letting outsiders in. However, the woman only laughs it off, though she becomes serious and asks if the rumors of being two outsiders were true, and restates it to Komoe's face: Where there really two of them? Suddenly, a ring comes from her cellphone before Komoe could reply. Her name is apparently Yomikawa, and that she has been called for Anti-Skill work, apparently a big one, and later leaves. After leaving, a familiar girl walks in to the faculty room, in a relatively slow pace. It is Aisa, bringing the book Komoe has asked for. She hands her the book, and asks with there really is a Kazakiri Hyouka in the school.

In the lively streets of Academy City, Shirai Kuroko of Judgment, finds a surprising figure among the crowds, Sherry Cromwell. She shoots a flair up into the sky, to which the student body immediately notices, and runs—it was an evacuation order. Sherry notices this as well. Kuroko introduces herself to Sherry, and tells her not to move. Slightly annoyed, Sherry tries to pull out her chalk from some pocket somewhere. However, she is surprised as Kuroko teleports before her. She grabs Sherry's arm, and slams her down the pavement, and then using her teleportation powers to teleport spikes on the ground to pin her down. After some light bragging from Kuroko, Sherry smiles as she has already written down the word Golem Ellis in cursive no less, on the ground. Suddenly, the tiles crack below Kuroko's feet, and she is caught by its tremendous force, unable to do anything. A large hand forms from the rocks and stones that have been flung from the air, and grabs her. And there, she sees the large, black, and rugged form, of a being formed from stone, wailing from its dark chasms a deep ululating voice. Kuroko is terribly shocked by this, as she did not realize that Sherry might've been an "esper" as well, and realizes that she needs to retreat. However, from afar, a cheap arcade coin is flipped, and the voice of an angry young woman fills the air, as a powerful orange streak flies through the air. The power strikes and pierces the thing's arm, destroying it, and although Kuroko falls, she manages to teleport into safety next to Mikoto's side. Mikoto says that the hand was merely a diversion, and presumes that since they are after Sherry, then it must mean that was an intruder, to which Kuroko confirms. Kuroko suddenly cries out, and has her face upon Mikoto's chest. Mikoto embraces her, and comforts her young kouhai. However, all is not what it seems. Suddenly, Kuroko grabs Mikoto and begins rubbing her face into Mikoto's bosom, much to Mikoto's horror.

Meanwhile, as the two laze about, Sherry is walking around the squares and courts of Academy City in the open. She begins talking about the origin and evolution of her power, and then begins to write down, and chant her spell. After writing upon several surfaces, Sherry claps and calls out the name Ellis. Then, the words that are written upon the surfaces form into eyes. Countless orbs looking at every possible direction. Then the eyes disperse, and Sherry is left alone, and wishes for Ellis to hurry.

Due to Yamisaka Ouma's story being transferred to the second season of Toaru Majutsu no Index, a continuity error exists in this episode, specifically, Touma's room remaining intact, though this event is not mentioned again in the novels as well.

Aisa being a girl who goes unnoticed, would later become a recurring joke in every Toaru Majutsu no Index-related media she would appear in. This would be prominent in the Toaru Majutsu no Index-tan specials, poking fun on her apparent lack of notability.

This marks the very first time espers and magicians, if one does not take Tsuchimikado Motoharu into account, do battle with each other.

In the scene outside of school, after Aisa is focused on for the first time after her introduction to the class, and her noticing Touma and company, there are two background characters that walk by. The characters look similar to Fukuzawa Yumi and Ogasawara Sachiko of Maria-sama ga Miteru.

The popular For Dummies series of books is referenced during the episode as a book for learing about AIM dispersion fields.

Several terms from Jewish mythology and Kabbalism is referenced in this episode, such as the Golem, Noah's Ark, and the origin of Man, and their relations with angels. Mos specifically, the Grigoris are referenced.

Index:"What should I do... This is a huge crisis I have yet to face..." ―regarding her lunch plans.

Mikoto:"You think I asked you calmly?! Even for me, I didn't know what to do... and since I couldn't come up with any other solution... I swallowed the embarassment and... begged you to do it!" ―To Touma after he references the fake date they had.

Komoe:"Mmm... his Power Level is 70000!" ―On possible applications of an AIM detecting ability.

Aleister:"For it is a restive horse that could rip apart the entire world, and it would be best to have a firm grip of the reins before it's too late." ―To Motoharu regarding the Imaginary Number District.

Aogami Pierce:"Hey, look at me, I purposely left them on the backburner just so that Komoe-sensei could give me a scolding!" ―To Touma after he mentions Motoharu not doing his homework.

Komoe:"Congratulations, goons! Better luck next time, kitties." ―To the students of her class after saying that the transfer student is a girl.

Index:"Don't worry Hyouka. Touma's hot-blooded and indecisive, and if it involves girls, he's the type that'll dive right into problems for her, but he's a good person." ―To Hyouka, regarding Touma's personality.

Hyouka:"Animals are much more cunning than humans, so he could probably tell the difference between you and me." ―Regarding Sphynx jumping out of her bosom.

Komoe:"Why is it that girls always trickle down to you wherever you are, Kamijou-chan?!" ―To Touma after she discovers him with Index and Hyouka.

Hyouka:"Friends that are able to fight with each other are the ones that are really close." ―To Index.

Hyouka:"The fact they can fight means they can forgive each other properly afterwards. It's like you can trust that person to not cut off the relationship even after a fight." ―To Index.

Aisa:"I'm a girl who goes unnoticed after all, huh?" ―Aisa after Touma gives her a cold expression.

Sherry:"In the beginning, there was primal clay. God created a form from the clay, bestowed life upon it, and called it 'Man'. This secret was passed to Man through the oral tradition of the fallen angels. However, this was a secret too great for Man to handle. Thus, the life born from my hand halts at a decaying mud doll. Mud-stinking golem, Ellis. Laugh and decay at my bidding." ―Sherry's incantation.